Chapter 3: Structure and Function of Cells

A complete set of vocabulary flashcards covering cell structure, membrane transport mechanisms, nucleic acids and protein synthesis, cellular organelles, and cellular respiration metabolic pathways.

Eukaryotes

Cells that possess a plasma membrane, nucleus, cytoplasm, and organelles with specialized functions.

Prokaryotes

Cells that lack a nucleus or true organelles, such as bacteria.

Micrometer ($\mu m$)

A unit of measurement equal to 1 millionth of a meter ($10^{-6}\,m$); most human cells measure approximately $10\,\mu m$.

Microvilli

Extensions of the cell membrane that increase surface area to promote metabolic efficiency.

Plasma Membrane

A selectively permeable lipid bilayer approximately $3.5\,nm$ thick that encloses the cell.

Phospholipids

Molecules forming the plasma membrane bilayer, featuring a polar head and a nonpolar tail.

Cholesterol

A lipid molecule within the plasma membrane that provides stability and makes the membrane more rigid.

Passive Transport

The movement of substances across a cell membrane from higher to lower concentration along a concentration gradient without energy consumption.

Osmosis

The diffusion of water across a membrane through membrane channels.

Isotonic Solution

A state where extracellular and intracellular solute concentrations are equal.

Hypotonic Solution

A state where extracellular solute concentration is lower than intracellular solute concentration, resulting in higher water concentration outside the cell.

Hypertonic Solution

A state where extracellular solute concentration is higher than intracellular solute concentration.

Facilitated Diffusion

Passive transport of a molecule across the membrane that requires a specific membrane protein, such as for glucose.

Active Transport

The movement of substances across a membrane from an area of lower concentration to an area of higher concentration requiring energy ($\text{ATP}$).

Sodium/Potassium Pump

An active transport mechanism that uses $\text{ATP}$ to expel three sodium ions ($\text{Na}^+$) for every two potassium ions ($\text{K}^+$) brought into the cell.

Endocytosis

Bulk transport mechanism requiring $\text{ATP}$ that moves materials into the cell.

Exocytosis

Bulk transport mechanism requiring $\text{ATP}$ that moves cellular wastes and materials out of the cell.

Nucleolus

A distinct structure inside the nucleus that synthesizes ribosomes.

Messenger RNA (mRNA)

Type of RNA that carries the genetic code or message from DNA in the gene to the cytoplasm.

Transfer RNA (tRNA)

Type of RNA that carries a specific amino acid and binds to an mRNA codon via its complementary anticodon during protein synthesis.

Ribosomal RNA (rRNA)

RNA constituent of the ribosome where mRNA and tRNA meet to assemble amino acids into proteins.

Transcription

The nuclear process in which DNA synthesizes or transcribes RNA.

Translation

The cytoplasmic process in which ribosomes read mRNA and assemble amino acids into a polypeptide chain.

Rough Endoplasmic Reticulum

Endoplasmic reticulum studded with ribosomes that is involved in protein manufacture and modification.

Smooth Endoplasmic Reticulum

Endoplasmic reticulum lacking ribosomes that functions in lipid synthesis.

Golgi Apparatus

An organelle that receives cellular substances from the endoplasmic reticulum, refines them, and packages them.

Peroxisomes

Membrane-bound vesicles that detoxify harmful substances such as $\text{H}_2\text{O}_2$ and alcohol.

Microtubules

Larger cytoskeletal filaments responsible for organelle and vesicle movement inside the cell.

Microfilaments

Small cytoskeletal fibers, such as actin, that aid in cell support.

Cilia and Flagella

Cellular movement structures characterized by a $9 + 2$ arrangement of microtubules.

Mitochondria

Double-membrane organelles containing inner membrane enzymes that break down nutrients to generate $\text{ATP}$.

Glycogen

A carbohydrate molecule used for short-term energy storage in animals.

Anabolism

Metabolic pathways that assemble large molecules to build cellular components and store energy, requiring enzymes and potentially $\text{ATP}$.

Catabolism

Metabolic pathways that break down molecules to recycle cell components and release stored energy.

Glycolysis

The initial step of glucose catabolism in the cytosol that splits glucose into $2\text{ pyruvate}$ molecules and yields $2\text{ ATP}$.

Preparatory Step

The cellular respiration stage that converts pyruvate to Acetyl CoA, a process blocked by arsenic.

Citric Acid Cycle

The stage of cellular respiration that extracts high-energy electrons via $\text{NADH}$ and $\text{FADH}_2$, producing $2\text{ ATP}$ and carbon dioxide ($\text{CO}_2$).

Electron Transport System

The mitochondrial stage of cellular respiration that uses high-energy electrons to produce the majority of $\text{ATP}$, using oxygen as the final electron acceptor.

Calorie

The amount of energy required to raise the temperature of $1\,kg$ ($1\,liter$) of water by $1\,^\circ\text{C}$.